The present invention relates generally to the field of systems computing, and more particularly to data sharing.
In mainframe computers, a Coupling Facility, or CF, is a piece of computer hardware which allows multiple processors to access the same data. A Mainframe Cluster relies on one or more Coupling Facilities (CFs). A coupling facility is a mainframe processor (runs with its own logical partition (LPAR), with dedicated physical CP, defined thru a hardware management console), with memory and special channels (CF Links), and a specialized operating system called Coupling Facility Control Code (CFCC). It has no Input/Output devices, other than the CF links. The information in the CF resides entirely in memory as CFCC is not a virtual memory operating system. A CF typically has a large memory on the order of several gigabytes. In principle, any mainframe can serve as a coupling facility. The CF runs no application software.
The CFCC uses an Internal Coupling Facility where the CFCC runs in a logical partition (LPAR) defined in standard processor complex and communicates over internal links within that processor complex hardware. Links to another processor unit are over networking cables. More than one CF is typically configured in a cluster for reliability and availability. Recovery support in the operating system allows structures to be rebuilt in the alternate CF in the event of a failure.